TEMPERATURE-CONTROLLED IONIC-CONDUCTIVITY SWITCHING IN POLY[OLIGO(OXYETHYLENE) METHACRYLATE] POLY(ETHYLENE OXIDE) LAYERED FILM

The present study is aimed to design the temperature-driven switching of the ionic conductivity in polymer electrolytes. First, thermotropic liquid crystalline molecule, 4'-ehtoxybenzylidene-4-n-butylaniline (EBBA), was sandwiched with poly (oligo (oxyethylene) methacrylate) (PMEO) containing LiClO4. A change in the ionic conductivity was observed by heating due to crystal/nematic phase change, but it was observed only in the first heating. On the other hand, the ionic conductivity of PEO sandwiched system showed drastic ionic conductivity jump which was attributed to the phase transition of the PEO. The temperature dependence of the ionic conductivity showed a good reproducibility in this system. The phase transition temperature was affected by the added salt concentration. This was comprehensible as freezing point depression of PEOs. The switching temperature was controllable in the range from -13-degrees-C to 52-degrees-C by the molecular weight of PEO and added salt concentration in the PEO. The formation of ion pair and aggregate ion was never observed by Raman spectroscopy in the range of salt concentration used in this experiment.